Making a Stylized Town Bus Animation in Maya, Substance 3D Painter & Arnold

Introduction

Hi, my name is Byeonghyeon Hwang, and I majored in animation at Hongik University in South Korea. I was very interested in CG animation, so I started studying. After a while, I directed several short animations and have now been working on various personal projects, which you can see on my ArtStation or website.

Now, I’m working as a Lighting Artist at Millionvolt Animation Studio in Seoul. I'm a Junior Artist who has been working for 9 months and now I'm taking part in a series of unreleased animations. 

The Town Bus Project

The Town bus project started as a simple idea from my friend Sunwoo.

When I was thinking about the topic of my personal work, she gave me her opinion, "Why don't you express a bus running on the road?" and I accepted it eagerly. My previous personal works were all still images, so I was interested in working with animation and thought I could have fun!

Most of the work took place after work, from 8 p.m. to dawn, I usually went to bed around 2-3 p.m.) There were times when I was tired, but I tried to produce the best quality I could. I mainly used Maya and Arnold for my work, as well as Nuke during compositing.

Production Plan

First of all, I wanted a very, very static and peaceful atmosphere. I asked myself, "How can I express this atmosphere in a visual and interesting way?" and thought of some conditions for this.

• Side view – Static image through a fixed cam.
• Diagonal Composition – Dynamic Application to Image with Slanted Floor
• Exaggeration – Expression of exaggeration shape, mood, and color.
• Animation – Bring the results to life through the animation of the bus.
• PBR-based realistic texture
• Have fun working – the most important part!

Based on the six conditions, I found images and artwork of various places that looked peaceful. I mainly referred to the "Luca" look dev (produced by Pixar) and collected many images to refer to the feeling of warm lighting. After that, I drew concept art by referring to images I found on the internet and photos I took myself.

In my work, I think it is important to draw concept art roughly because it is the stage where you can quickly modify the layout by checking the appearance of the results before moving on to CG work, and a better image can come out based on this process. Not only that, but it also helped me list the props I needed to make. With the written prop list, I was able to establish the following work plan:

• Number of props to make
• Props design
• Direction of reference

Based on this, I collected reference images and moved on to Maya.

3D Blocking

Before I made the assets, I did the 3D blocking work. I adjusted the Transform value of the dummy object and specified the scene scale and shape of the props as well as color. During the production process, it is often necessary to rework already created assets for modifications, this is the cause of the delay in production, so I tend to modify as much as possible in a relatively easy stage to avoid this.

Through pre-visualization, such as the 3D blocking process, I was able to get feedback on what was strange and what needed to be fixed. This way, when I found something I needed to fix, I edited it until I got the image I wanted. Despite that, as the work progressed, the wooden fence disappeared on the way.

Assets

Most of the asset work processes were done this way – I started building floors and walls in this order:

1) The ground and the wall

In the case of the floors and the walls, the texture detail was very important because it took up a large portion of the screen. First, I made a simple base model in Maya, then I imported it into ZBrush and proceeded to sculpt.

After sculpting the form, I expressed the damage using various alpha brushes that I bought on ArtStation. Next, used a black and white image of asphalt with the noise. Using the Layer, I was able to reduce the time required for modification. After that, I used Substance 3D Painter to work on the texture.

In this process, the Cavity and Curvature maps extracted from ZBrush were very useful. The Cavity map can be handy if you have an organic sculpt and you want to mask pores or other similar details. You can also blend it on top of your Diffuse to add more complexity to your textures. Here's the guide on how to extract a Cavity map.

The most important part of asphalt and wall texturing was the Base Color map production. Keeping in mind the fact that even simple gray-looking asphalt actually contains a variety of colors, I tried to express it realistically based on the reference image.

2) The buildings

The exterior of the buildings had to be designed with a deformer. With this design, I thought it would be fun even on a static screen.

Based on the design that had been determined in the blocking stage, I modeled it in Maya. You can see the tiles on the roof in zigzag, it was important to make this deformation so that the audience could enjoy the appearance of the object.

After the modeling was completed, the texturing was done in Substance 3D Painter.

This is one of the parts where I tried to make various changes to the Base Color during the texturing work. I made a gradation mask using the Position map and added the green color. 

As you can see, the Base Color became richer. In order to express the color of the building, various masks were used, and finally, a satisfactory result was obtained.

3) The tree and the plants

I wanted the shapes of the trees and plants to be expressed in a simple form. I thought it was too much work to do in Maya, so I used SpeedTree.

First, I set the dummy object created in Maya to target using the Mesh Forces. Based on this function, I was able to make wood and grass very easily.

Not only that, it was a great advantage to be able to export and utilize the animation cache where the grass shakes in the wind by setting the wind value in SpeedTree. However, when I looked at the viewport, I thought the wind animation strength was right, but when I looked at the final rendering results, it almost didn't change. I'll keep this in mind when I proceed to the next project.

After that, I adjusted the Speedtree export options: setting five materials to be registered randomly on the leaves, I constructed Hypershade nodes in Maya's shading operation to represent different colors of the leaves. But I think I could have made the node graph in a slightly more efficient way.

4) The bus

It was made the same way as in the previous asset production pipeline. With the concept of an old bus, I tried to express a weathering effect with some dented and rusty parts.

At the time of the work process, the overall smoothness and flatness looked awkward (like a new car), but I was able to create a natural surface by connecting large noise textures to the height channel. If you use this way, you have to be careful because the seam part of the UV may become weird.

The dust expressions utilized black and white images that adjusted the value of photos taken directly or downloaded from the internet. It's a simple task, but I recommend it because it gives you realistic texture results.

My friend Sungjin-Han helped me with the rigging work. He created a lot of the necessary functions, so I was able to easily animate them.

Lighting & Rendering

The lighting work progressed in 4 steps.

First, I installed a key light and a fill light to set the basic atmosphere. Key lights are installed with an emphasis on the angle and intensity of light. For the fill light, an HDRI dome light was used. I multiplied a color-constant node to the HDRI image to make it easier to control the color of the shadow.

After that, using additional lights and light blockers, I proceeded to the lighting work like painting. I used not only the built-in light blocker function in Arnold but also the plane geo as a blocker to control the shadow area. Using the references collected before, I set up the lighting so that the audience can feel a warm and calm afternoon.

Compositing

After completing the rendering, I worked on compositing in Nuke.

I added a grade node to the Light Path Expressions AOVs that was imported from the Maya render setup and proceeded with color grading by adjusting the color.

I made the color a little warmer and tried to make the volume look better. I also brought the unique colors of the objects to life, the purpose of this was to add more cuteness to the image.

Cryptomatte was useful in this process, it was really easy to adjust when you wanted to change the color of a particular object or material.

Final Renders

And finally, the work is done. It was never easy, but it was a project that taught me a lot. Above all, I was satisfied that the image I had planned and imagined was well-reflected. I think it was very helpful to have a detailed plan on how to proceed with the work.

I'll return with a better project next time!

Byeonghyeon Hwang, Lighting Artist

Interview conducted by Arti Burton